In recent months, the unmanned spy planes have been put to work fighting fires and flooding. Privacy watchdogs are uneasy.

Most days, U.S. Customs and Border Protection Officer David Gasho sends three unmanned spy planes into the skies over the rugged Sonora Desert to hunt for drug smugglers crossing into southern Arizona from Mexico.

But in mid-June, as the largest wildfire in Arizona history raged, Gasho sent one of the Predator B drones soaring over residential neighborhoods in search of another threat — rogue brush fires. Working from an air-conditioned trailer, his crew aimed an airborne infrared camera through thick smoke and spotted a smoldering blaze.

Using coordinates fed from the drone, airborne firefighters then doused the hot spot from helicopters and watched over a secure Internet feed as the heat signature of the flames cooled.

It was the latest example of once-secret military hardware finding routine civilian uses. Seven surveillance drones are chiefly used to help patrol America's northern and southern borders. But in recent months, they also have helped state and local authorities fight deadly fires, survey damage from floods and tornadoes, and inspect dams and levees.

"People are constantly coming up and wanting a piece of that Predator pie," said Gasho, a former commercial pilot who heads the Customs and Border Protection air operations in Sierra Vista, Ariz., standing beside one of the drones at Libby Army Airfield.

Between March and July, for example, dozens of drone missions were flown between Grand Forks, N.D., and Columbia, Mo. The Predators provided first responders and engineers with live video and radar images of widespread flooding along the Soris, Red and Missouri rivers.

During the summer, drones flew along the Louisiana Gulf Coast and up the Mississippi River to inspect flood damage and the integrity of levees.

Operators studying the drone feeds look for signs that a levee is bulging from pressure of floodwaters, and advise where a swollen river may first overflow its banks. Local officials can then order evacuations and direct help to vulnerable neighborhoods.

In addition to three Predators in Arizona, Customs and Border Protection crews operate two drone aircraft out of Grand Forks, N.D., one from Corpus Christi, Texas, and another in Cocoa Beach, Fla. Plans call for adding three more drones later this year.

But some see dangers as well as benefits in the arrival of the drones.

Privacy experts warn that few guidelines restrict eye-in-the-sky coverage. Jay Stanley, a senior analyst on privacy and technology at the American Civil Liberties Union, says the unregulated use of drone aircraft "leaves the gates wide open for a dramatic increase in surveillance of American life." The drones can detect all manner of activities: from its usual altitude of 20,000 feet, a drone camera can tell if a hiker eight miles away is carrying a backpack.

And aviation security experts worry that pilots operating drones from distant locations may not be able to see and avoid other aircraft in busy air corridors.

"The problem is safety [and] how to share airspace with manned aircraft," said Michael Barr, who teaches aviation safety at USC.

The Homeland Security Department's first drone crashed in 2006. When a console froze during the flight, the ground-based pilot accidentally switched off the fuel line to the engine.

"This was one of these instances where he would have been better off not touching it," said Gasho. "He just panicked. Hit the button and threw away a $7-million airplane."

The crash missed a residential area by 1,000 feet and brought additional scrutiny from the Federal Aviation Administration. It established a special board to approve airspace for use by unmanned aerial vehicles.

In emergencies, like floods and fires, the FAA will fast-track the approval process, said FAA spokesman Les Dorr.

"But that doesn't short-circuit any of the safety concerns," Dorr said. "We still evaluate it to make sure it can fly safely without danger to people on the ground or pilots in the air."

Indeed, the FAA has yet to approve a request to authorize use of a Customs and Border Protection drone to help firefighters in Texas battle fierce wildfires there last week.

The ability to sense and avoid other aircraft is the "big bugaboo with unmanned aircraft that has prevented them from meeting federal regulations to fly," said Bill English, senior air safety investigator at the National Transportation Safety Board. The FAA requires drone pilots to have direct eye contact with the plane during takeoff and landing to avoid collisions with other aircraft.

Yet because no pilots are on board and the planes can stay aloft for 20 hours at a time, the drones are well suited for dirty, dull and dangerous work.

In April, when ice piled up under bridges and caused the Red River to overflow its banks, a Customs and Border Protection drone flew out of Grand Forks to survey the river around Oslo, Minn. Watching the live footage from the unmanned plane, officials were able to spot a clay levee that appeared about to break and quickly shored it up.

Without the live footage, engineers and rescue teams might not have reached the right place in time, officials said.

"We would have lost a small town of 50 to 80 homes," said Kim Ketterhagen, the mutual aid coordinator for Minnesota's homeland security and emergency management department.